Typically, bags of solutions for intravenous injection of patients are prepared manually by pharmacists or pharmacist's aides. Each solution must be tailored to the particular need of the patient with respect to composition, quantity and type of medicament, and pH level. Variations from required levels can have deleterious, even fatal, consequences for the patient. Pharmacists and their assistants are highly trained and conscientious professionals. Nonetheless, under the pressures of time and environment, these professionals can make errors. In addition, the need to keep the final preparation sterile requires costly and time-consuming measures on the part of those who prepare the solutions.
Heat sterilization of solutions for intravenous injection, for example as part of a total parenteral nutrition system can lead to carmelization of the injectable sugars, which can have enormously negative consequences for the health of the patient. In my prior U.S. Pat. No. 4,906,103 I disclosed a system for the cold sterilization of solutions which completely avoids the hazards of heat sterilization. In my prior U.S. Pat. No. 5,196,001 I disclosed a preparation assembly and unit dose medicament containers for use in a cold sterilization system which permitted controlled pre-preparation dosing of medicaments.
Great strides have been made in automatic dispensing of solid pills and powders by way of computer controlled robotic assemblies. With greater attention to costs at all levels of the health care system, efforts have been made to limit the direct intervention of doctors and pharmacists in dispensing of medications, while at the same time maintaining adequate control by these professionals. Solid pills and capsules are by their nature suited to dispensing in unit doses, but the remotely operated drawers and dispensers which are adequate for pills are not effective for the preparation of individualized injectable solutions. Furthermore, robotic devices for dispensing liquids from a storage vessel of liquid present serious concerns in the preparation of solutions for administration to humans. Typically an aliquot of liquid would be dispensed by a micropump. Yet pumps are subject to malfunctions, and great care needs to be taken to quality check whether the desired quantity of liquid has actually been dispensed. In any event, no physical record remains to verify the amount and type of liquid dispensed. What is needed is a consistent and effective apparatus for preparing and dispensing liquid medicament solutions.